I can't honestly accept that the transition was "smooth". Devices that used to work and used to get updates simply stopped at one point. Because Apple likes to couple OS updates and app updates, and also believes backward compatibility is for [not their customer], I had to talk a grad student down when he sent his thesis to a department chair who opened it, saved it in a non-compatible version of Pages, and sent it back. He could not open that file without upgrading his...2 year old computer?

The transition wasn't smooth unless you had a corporate backer who paid for your milti-thousand-dollar hardware regularly.